Just because Amazone owns Twitch doesn't mean they pay themself, they are still two distinct legal entities and Twitch is competing with other non Amazone owned companies (e.g. Kick) for the same resources. If Twitter would not pay Amazone I think it might even somewhat fall under competitive distortion/unfair competition.
Large steams do amortize cost while the bandwidth cost is somewhat scaling per viewer there are other cost which scale per used resolution and per region the stream is streamed to. So on a per-view bases large streams are often not the most expensive. But very small streams with viewers across continents have the highest per-view cost.
AD revenue is split but the main problem is Twitch ADs are not worth much and a bought way to little, often leading to no ADs playing at all for many (non US) regions.
>they play 3 minutes of ads that interrupts the entire content every 10 minutes.
They do not (typo?), it's depending on the streamers setup but ADs are normally more in the 3min per hour basis which is fine to be honest. There are sometimes some additional banner ads but they don't cover the content, don't "play" and are not that disruptive. And there is Twitch Turbo which disables all ADs but streamers still get the AD money. Through that isn't worth it's money for a lot of people.
